1. Field of the Invention
The present invention relates to an organic electroluminescent device of the active matrix (AM) and passive matrix (PM) types, and a method for manufacturing the same. Particularly, the present invention relates to an organic electroluminescent device and a method for manufacturing the same, capable of achieving high resolution and big size by decreasing a space between the anode electrodes.
2. Description of the Related Art
Organic electroluminescence is a phenomenon wherein excitons are formed in an organic (low molecular or high molecular) material thin film by recombining holes injected through an anode with electrons injected through a cathode, and a light of specific wavelength is generated by energy from thus formed excitons. The basic structure of an organic electroluminescent device using the phenomenon and a method for manufacturing the same will be described hereinafter.
FIG. 1 is a plan view of an organic electroluminescent device, in accordance with the related art. FIG. 2 is a cross-sectional view of the organic electroluminescent device of FIG. 1, as taken along line A-A.
The basic structure of an organic electroluminescent device includes a glass substrate 1, an anode electrode layer 2 formed on the upper side of the glass substrate 1, an organic material layer 3 (hereinafter, referred to as “organic EL layer”) formed on the anode electrode layer 2, and a cathode electrode layer 4 formed on the organic EL layer 3.
The organic EL layer 3 has a structure wherein a hole transport layer, a light emitting layer and an electron transport layer are stacked in order. Each cathode electrode layer 4 maintains a certain space from adjacent cathode electrode layers 4. The anode electrode layer 2 acts as an anode electrode, and the cathode electrode layer 4 acts as a cathode electrode.
A wall 5 separates two adjacent cathode electrode layers 4. The wall 5 is formed in an area between two adjacent cathode electrode layers 4. The wall 5 is separated from the anode electrode layer 2 by an insulating layer 4a. Although organic material and cathode electrode material are deposited on the upper side or top of each wall 5 during the processes of forming the organic EL layer 3 and cathode electrode layer 4, neither functions as a component of the device.
The organic electroluminescent device having the above structure is manufactured by the following processes.
First, a plurality of anode electrode layers 2 are deposited on a glass substrate 1, and then an insulating layer 4a is formed on the entire surface area of the substrate 1 except predetermined areas (luminescent areas).
Then, a plurality of walls 5 crossing the anode electrode layers 2 are formed thereon, followed by forming organic EL layers 3 and cathode electrode layers 4 on the entire structure including the walls 5.
In the organic electroluminescent device of the related art, illustrated in FIG. 1, predetermined spaces exist between anode electrode layers 2. In a high resolution display device, in which the number of luminescent areas per unit area is increased, these spaces between the anode electrode layers 2 become a major concern. Since the spacing between anode layers 2 is predetermined, a large number of luminescent areas requires an increase in the size of the display device to accommodate the many required spaces between the anode electrodes layers 2, which is counter to the higher resolution goal, i.e. more luminescent areas per unit area.